. Abstract-Software rejuvenation is a proactive software control technique that is used to improve a computing system performance when it suffers from software aging. In this paper, a two-granularity inspection-based software rejuvenation policy, which works as a closed-loop control technique, is proposed. This policy mitigates the negative impact of two-level software aging. The two levels considered are the user-level applications and the operating system. A Markov regenerative process model is constructed based on the system condition. We obtain the degradation rate of the application software and operating system from fault injection experiments. The diagnostic accuracy of the adopted monitor and analysis system, which is applied to inspect the application software and operating system, is considered as we provide the optimal rejuvenation strategies. Finally, the availability and the overall loss probability with their corresponding optimal inspection time intervals are obtained numerically based on the parameter values estimated from the experiments. Experimental results show that two-granularity software rejuvenation is much more effective than traditional single-level software rejuvenation. In our experimental study, when two-granularity software rejuvenation is used, the unavailability and the overall loss probability of the system were reduced by 17.9% and 2.65%, respectively, in comparison with the single-level rejuvenation.Index Terms-Diagnostic accuracy, Markov regenerative process (MRGP), multigranularity software aging, overall loss probability, software rejuvenation.
Objective The present study aimed to investigate the predictive value of some indexes, such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), systemic inflammatory response index (SIRI), and systemic immune-inflammatory index (SII) in the survival of nasopharyngeal carcinoma (NPC) and provide reference for the treatment. Methods A retrospective analysis was performed on 216 patients from 2016 to 2018. The cutoff values of these indexes were determined by the receiver operating characteristic (ROC) curve. The prognostic value of the indexes was evaluated according to the rate of overall survival (OS), regional recurrence-free survival (RRFS), locoregional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS). Results The survival analysis showed that NLR ≤2.695 (P = 0.017) and PLR ≤140.065 (P = 0.041) were associated with poor OS; however, the LMR and SIRI showed no significant statistical significance. NLR ≤2.045 (P = 0.018) and PLR ≤125.605 (P = 0.003) were associated with poor RRFS, LMR ≤2.535 (P = 0.027) and PLR ≤140.065 (P = 0.009) were associated with poor DMFS, NLR ≤2.125 (P = 0.018) and PLR ≤132.645 (P = 0.026) were associated with poor LRRFS, respectively. Logistic regression analysis showed that low LMR (≤2.535) was significantly inferior in OS (HR 23.085, 95% CI 3.425–155.622, P = 0.001) and DMFS (HR 22.839, 95% CI 4.096–127.343, P < 0.001). Moreover, low PLR (≤140.065) remained significantly related to worse OS (HR 11.908, 95% CI 1.295–109.517, P = 0.029) and DMFS (HR 9.556, 95% CI 1.448–63.088, P = 0.019). Conclusion The index LMR and PLR can be used for predicting survival in NPC patients.
Background To evaluate the prognostic value of the ratio of the standard uptake value of the lymph node and primary tumor before the treatment of locally advanced nasopharyngeal carcinoma and examine the prognostic value of the tumor metabolic parameters (SUVmax, MTV, and TLG) of the lymph node and primary tumor of locally advanced nasopharyngeal carcinoma. Methods A total of 180 patients with locally advanced nasopharyngeal carcinoma diagnosed pathologically from January 1, 2016 to December 31, 2018 were selected, and the MEDEX system was used to automatically delineate the SUVmax, MTV, and TLG of the lymph node metastases and nasopharyngeal carcinoma primary tumor. In addition, the ratio of LN-SUVmax (SUVmax of the lymph node metastases) to T-SUVmax (SUVmax of the nasopharyngeal carcinoma primary tumor) was calculated, and a ROC curve was drawn to obtain the best cut-off value. Kaplan–Meier and Cox regression models were used for survival and multivariate analyses, respectively. Results The median follow-up period for participants was 32 (4–62) months. Univariate analysis showed that age (P = 0.013), LN-SUVmax (P = 0.001), LN-TLG (P = 0.007) and NTR (P = 0.001) were factors influencing the overall survival (OS). Factors affecting local progression-free survival (LPFS) were LN-SUVmax (P = 0.005), LN-TLG (P = 0.003) and NTR (P = 0.020), while clinical stage (P = 0.023), LN-SUVmax (P = 0.007), LN-TLG (P = 0.006), and NTR (P = 0.032) were factors affecting distant metastasis-free survival (DMFS). Multivariate analysis showed that NTR was an independent influencing factor of OS (HR 3.00, 95% CI 1.06–8.4, P = 0.038), LPFS (HR 3.08, 95% CI 1.27–7.50, P = 0.013), and DMFS (HR 1.84, 95% CI 0.99–3.42, P = 0.054). Taking OS as the main observation point, the best cut-off point of NTR was 0.95. Kaplan–Meier results showed that the 3-year OS (97.0% vs 85.4%, χ2 = 11.25, P = 0.001), 3-year LPFS (91.3% vs 82.1%, χ2 = 4.035, P = 0.045), and 3-year DMFS (92.3% vs 87.9%, χ2 = 4.576, P = 0.032) of patients with NTR < 0.95 were higher than those with NTR > 0.95. Conclusions High NTR before treatment indicates a poor prognosis for patients with nasopharyngeal carcinoma. This can serve as a reference value for the reasonable treatment and prognosis monitoring of such patients.
Purpose: The aim of this study is to explore the robustness and accuracy of consensus contours with 225 nasopharyngeal carcinoma (NPC) clinical cases and 13 extended cardio-torso simulated lung tumors (XCAT) based on 2-deoxy-2-[$$^{18}$$ 18 F]fluoro-D-glucose ($$^{18}$$ 18 F-FDG) PET imaging. Methods: Primary tumor segmentation was performed with two different initial masks on 225 NPC $$^{18}$$ 18 F-FDG PET datasets and 13 XCAT simulations using methods of automatic segmentation with active contour, affinity propagation (AP), contrast-oriented thresholding (ST), and 41% maximum tumor value (41MAX), respectively. Consensus contours (ConSeg) were subsequently generated based on the majority vote rule. The metabolically active tumor volume (MATV), relative volume error (RE), Dice similarity coefficient (DSC) and their respective test–retest (TRT) metrics between different masks were adopted to analyze the results quantitatively. The nonparametric Friedman and post hoc Wilcoxon tests with Bonferroni adjustment for multiple comparisons were performed with $$P<$$ P < 0.05 considered to be significant. Results: AP presented the highest variability for MATV in different masks, and ConSeg presented much better TRT performances in MATV compared with AP, and slightly poorer TRT in MATV compared with ST or 41MAXin most cases. Similar trends were also found in RE and DSC with the simulated data. The average of four segmentation results (AveSeg) showed better or comparable results in accuracy for most cases with respect to ConSeg. AP, AveSeg and ConSeg presented better RE and DSC in irregular masks as compared with rectangle masks. Additionally, all methods underestimated the tumour boundaries in relation to the ground truth for XCAT including respiratory motion. Conclusions: The consensus method could be a robust approach to alleviate segmentation variabilities, but did not seem to improve the accuracy of segmentation results on average. Irregular initial masks might be at least in some cases attributable to mitigate the segmentation variability as well.
Background: To evaluate the prognostic value of the ratio of the standard uptake value of the lymph node to the primary tumor before treatment of locally advanced nasopharyngeal carcinoma.Methods: A total of 180 patients with locally advanced nasopharyngeal carcinoma diagnosed pathologically from January 1, 2016, to December 31, 2018, were selected, and the MEDEX system was used to automatically delineate lymph node metastases SUVmax (LN-SUVmax) and nasopharyngeal carcinoma primary tumor SUVmax (T-SUVmax). In addition, the ratio NTR of LN-SUVmax to T-SUVmx was calculated, and an ROC curve was drawn to obtain the best cut-off value. Kaplan–Meier and Cox regression models were used for survival and multivariate analyses, respectively.Results: The median follow-up period of 180 patients was 32 (4–62) months. Univariate analysis showed that age (P = 0.013), LN-SUVmax (P = 0.001), and NTR (P = 0.001) were factors influencing overall survival (OS). Factors affecting local progression-free survival (LPFS) were LN-SUVmax (P = 0.005) and NTR (P = 0.020), while clinical stage (P = 0.023), LN-SUVmax (P = 0.007), and NTR (P = 0.032) were factors affecting Distant metastasis-free survival (DMFS). Multivariate analysis showed that NTR was an independent influencing factor of OS (HR = 3.00, 95%CI = 1.06–8.4, P = 0.038), LPFS (HR = 3.08, 95%CI = 1.27–7.50, P = 0.013), and DMFS (HR = 1.84, 95%CI = 0.99–3.42, P = 0.054). Taking OS as the main observation point, the best cut-off point of NTR was 0.95. Kaplan–Meier results showed that the 3-year OS (97.0% vs. 85.4%, c2=11.25, P = 0.001), 3-year LPFS (91.3% vs. 82.1%, c2 = 4.035, P = 0.045), and 3-year DMFS (92.3% vs. 87.9%, c2 = 4.576, P = 0.032) of patients with NTR < 0.95 were higher than those with NTR > 0.95.Conclusions: High NTR before treatment may lead to poor prognosis of patients with nasopharyngeal carcinoma. This can serve as a reference value for the reasonable treatment and prognosis monitoring of such patients.
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